Auburn research gaining new insights into kudzu bug behavior, control

• The biggest breakthrough of all is the detection of a native parasitoid found in the guts of several kudzu bugs that have been dissected.
• The parasitoid ultimately could reduce the kudzu bug’s numbers substantially over the next few years and may also prove to be an effective biological method to complement future control strategies.

Two grants have helped an Alabama Extension specialist and Auburn University professor gain several breakthrough insights into the kudzu bug.

Xing Ping Hu, an Alabama Cooperative Extension System entomologist and Auburn University professor in the Department of Entomology and Plant Pathology, says her research has gained several breakthrough insights into the virulent kudzu bug, including the discovery of a native predator that could go a long way toward reducing the pest’s numbers.

The first grant of $50,000 was awarded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture, while the second, totaling $30,000, was provided by the Extension Integrated Pest Management Coordination and Support Program to support Hu’s efforts to deliver her research findings to the people affected by the pest.

Her initial research findings have confirmed the pest’s remarkable adaptability to new environments.

“Since its detection in 2009, this stink bug has developed from an urban nuisance to a serious bean crop pest throughout the Southeast,” Hu says, adding that its rapidly expanding range, explosive population growth, severe damage to legume crops and vegetables, repulsive smell and difficulty to control have contributed to its elevated pest status.

“Sometimes you will see them feeding voraciously on all kinds of plants, including ornamental and horticultural plants, particularly in early spring and late fall when kudzu and soybean plants are unavailable or unsuitable for feeding.”

Despite a special affinity for legumes, such as kudzu and soybeans, they can adapt to many other species. To sustain their long flights during migration, the bugs have even been detected feeding on Queen Anne’s Lace, a common wild plant found along many Alabama roadsides.

Hu has also noted a penchant for long beans and green beans.

Can do serious damage

“If a kudzu bug population grows large enough, it’s capable of wiping out these two crops,” Hu says. “In fact, we have photos showing as many as 50 bugs on only one long bean pod.”

Some plants have died from bug infestations. The same holds true for several other vegetable corps, such as lima beans, runner beans and string beans.

Hu has also discovered the female’s ability to store sperm during the over-wintering period — a rare trait among insects and one that provides the species with an especially valuable survival tool.

“The sperm can survive the entire winter, after which the stored sperm is released and the eggs fertilized,” she says. “What this means is that a female kudzu bug doesn’t need the presence of males when she flies to a new location to over-winter.”

Hu has also gained new insights into how females lay their eggs, depositing them strategically in early spring before the primary hosts, kudzu and soybeans, begin budding and leafing.

She says the females often deposit egg masses on low plants close enough for fast-growing kudzu to reach. Females have also been found depositing egg masses on tall plants and trees farther away so that the hatched larvae are blown by wind into the kudzu — a highly evolved dispersal method, she says.

Hu has also determined that kudzu bugs migrate into soybeans only after the plants have reached a foot in height.

She hopes these findings will provide homeowners and farmers alike with more effective methods to remove habitats that promote the pest’s spread.

The biggest breakthrough of all is the detection of a native parasitoid found in the guts of several kudzu bugs dissected by Hu’s graduate student researcher, Julian Golec.

The parasitoid, which Hu has determined to be a fly, ultimately could reduce the kudzu bug’s numbers substantially over the next few years and may also prove to be an effective biological method to complement future control strategies.

“The presence of this parasite in the bugs we’ve detected is unusually high,” she says. “We’ve even seen the larvae crawl out from several of the insects, pupate on the ground and emerge into flies, which, in turn, affect other bugs.”

Hu has determined the family and genus of the fly and hopes to release it within the next few weeks. Her next research priority is to determine conditions for optimizing the parasite’s numbers.

“The discovery of this parasite is especially good news, as it may provide a viable alternative to an imported wasp species, allowing nature to take the exotic kudzu bug to task,” Hu says.

To date, the pests have spread to 56 of Alabama’s 67 counties since 2009.